A medical laser apparatus comprises: a solid laser oscillating source which emits a beam of a wavelength 1 in an infrared region of approx. 1040 nm to approx. 1080 nm; a first fiber-based Raman shifter including a first Raman fiber which generates, when receives the 1-beam from the laser oscillating source, a first-order Stokes beam of a wavelength 2 different from the wavelength 1 by stimulated Raman scattering, the first Raman fiber being formed with a pair of fiber Bragg gratings which forms a resonator for the 2-beam; a first nonlinear crystal which wavelength-converts the 2-beam outputted from the first Raman wavelength shifter to a second harmonic beam of a wavelength 2 in an orange region of approx. 580 nm to approx. 600 nm; and a light guiding optical system which guides the 2-beam to a treatment part.